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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    /**
     * 创建函数，生成当前时间字符串
     * 2021-10-15 10:17:20
     * 作为函数的返回值返回
    */
   function identify(num){
       return num < 10 ?"0"+num:num;
   }

   function createTime(){
        var date1 = new Date();

        var year = date1.getFullYear();
        var month = date1.getMonth() +1;
        var day = date1.getDate();

        var hour = date1.getHours();
        var min = date1.getMinutes();
        var sec = date1.getSeconds();

        month = identify(month);
        day = identify(day);
        hour = identify(hour);
        min = identify(min);
        sec = identify(sec);

        var result = year +"-"+month +"-"+day +" "+hour +":"+min +":"+ sec;
        return result;
   }
   document.write(createTime()+"</br>");
   document.write((new Date).toLocaleString());
</script>
</html>